This invention relates to reconfigurable manufacturing system (as illustrated in FIG. 1) and methods for designing and changing the production capacity of same.
Most medium and high-volume manufacturing industries currently use a portfolio of dedicated manufacturing lines (DML""s) and flexible manufacturing systems (FMS""s) to produce their products. DML""s, or transfer lines, are based on fixed automation and produce the core products of the company at high-volume. These lines are customized hardware lines that can control cutting tools in fixed directions determined at the design stage. They are designed to produce a single product and cannot be changed. Each dedicated line typically produces a single part (e.g., a pump housing). The dedicated lines are economical when large numbers of the same part are to be produced for a period of several years or more.
FMS""s produce a variety of products on the same system. They typically consist of computer numerically controlled (CNC) machines, and other programmable automation. CNC machines often use large tool magazines and several axes-of-motion to provide general flexibility which has the potential to produce a variety of parts of different types. But in many cases not all these axes-of-motion are utilized in the production of each part, which means that the machine is underutilized and its initial cost is partially wasted. Typically, the structure of each FMS and the structure of its CNC machines cannot be changed. The production capacity of FMS""s is fixed and is usually lower than that of dedicated lines, because their initial cost is higher.
The common denominator for the current two types of manufacturing systems (i.e. dedicated and flexible) is that they use fixed structure and fixed hardware (as illustrated in FIG. 2).
However, medium and high-volume manufacturers are now facing new market conditions characterized by: (i) pressure to quickly introduce new products at low cost, and (ii) large fluctuations in product demand. To cope with these needs and to stay competitive, manufacturing companies must possess a new type of manufacturing system that is very responsive to global markets; a system whose production capacity is adjustable to fluctuations in product demand, and which is designed to be upgradable with new functionality needed to produce new products with tighter product specifications. Current systems, even so-called flexible manufacturing systems, do not have these characteristics.
U.S. Pat. No. 5,691,945 discloses a technique for reconfiguring a high density memory.
U.S. Pat. No. 5,570,292 discloses an integrated method and apparatus for selecting, ordering, and manufacturing art glass panels.
U.S. Pat. No. 5,247,861 discloses a method of manufacturing laminated plastic tooling and tooling produced thereby.
U.S. Pat. No. 4,816,757 discloses a reconfigurable integrated circuit for enhanced testing in a manufacturing environment.
U.S. Pat. No. 4,807,108 discloses a product realization method.
U.S. Pat. No. 4,783,782 discloses a manufacturing test data storage apparatus for a dynamically reconfigurable cellular array processor chip.
U.S. Pat. No. 5,155,679 discloses a set-up optimization method of flexible manufacturing systems.
U.S. Pat. No. 5,456,332 discloses a multiple-degree of freedom vehicle which employs a compliant linkage.
U.S. Pat. No. 5,559,696 discloses a mobile robot internal position error correction system.
Other related publications include:
Goldman, S., Nagel, R. and K. Preiss, 1995, AGILE COMPETITORS AND VIRTUAL ORGANIZATIONS, 1995;
Hu, S. J., 1997, xe2x80x9cStream of Variation Theory and Its Application to Body Assemblyxe2x80x9d, CIRP ANNALS, 1997;
Koren, Y, Pasek, Z. J., Ulsoy, A. G. and U. Benchetrit, xe2x80x9cReal-Time Open Control Architectures and System Performancexe2x80x9d, ANNALS OF THE CIRP, Vol. 45, No. 1, 1996; and
Villasenor, J. and W. H. Mangione-Smith, 1997, xe2x80x9cConfigurable Computingxe2x80x9d, SCIENTIFIC AMERICAN, June 1997.
An object of the present invention is to provide a reconfigurable manufacturing system (RMS) including reconfigurable machines, reconfigurable controllers, and a reconfigurable material handling system, as well as methodologies for its systematic design and changing its production capacity including reconfiguration and ramp-up (see FIG. 3).
In general, a reconfigurable manufacturing system (RMS) is one designed at the outset for rapid adjustment of production capacity and functionality, in response to new market circumstances, by basic change of its structure as well as its hardware and software components.
Another object of the present invention is to provide a reconfigurable manufacturing system (RMS) which allows rapid changes in the system structure simultaneously with changes in the structure of machines or apparatus that make up the system. The invention also enables the rapid conversion of the system and its machines from production of one product to another by relocating their basic building modules and having means for their quick and reliable integration. This can be done economically by designing a system to produce parts of the same part-family, or product-family (xe2x80x9cproduct familyxe2x80x9d means, for example, several types of engine blocks or several types of microprocessors). This enables the quick and economic conversion of the reconfigurable manufacturing system from the production of one part or product to another, where both products are from the same product family.
In carrying out the above objects and other objects of the present invention, a reconfigurable manufacturing system (RMS) having an adjustable structure to quickly change from a first desired production capacity to a second desired production capacity to manufacture a desired mix of products from a family of products is provided. The system includes a plurality of work stations including reconfigurable machines, a control system including a plurality of reconfigurable controllers for controlling the reconfigurable machines, and a reconfigurable material handling system in communication with the control system for transporting material or parts between the work stations. The reconfigurable machines and controllers are modular to permit rapid and reliable integration of the machines and controllers during a change in the structure of the RMS so that the RMS will have the second desired production capacity.
Preferably, the adjustable structure of the RMS also allows the RMS to quickly change from a first functionality to a second functionality (which is typically achieved by adding new features to existing machines of the RMS).
The material handling system may include a plurality of conveyor modules for moving parts or materials between the work stations. Alternatively, the material handling system may include a plurality of wireless-controlled transport vehicles for moving parts or materials between the work stations.
The machines may include reconfigurable machines, CNC machines, modular machine tools, and other machines, at least one of which is capable of performing machining operations.
The controllers typically include modular, open-architecture controls. The machines, the controllers and the material transport system all obey an open standard so that the machines, the controllers and the material transport system can be improved and upgraded rather than replaced.
In one embodiment, at least one of the machines is a CNC machine and at least one of the machines is a machine having reconfigurable hardware components.
At least one of the controllers is a controller having reconfigurable software components or modules. Each of the controllers, the machines and the material transport system has an interface to permit rapid and reliable mechanical and electrical integration with the rest of the RMS.
The family of products has at least one dominant feature and wherein the controllers and the machines are customized to fit the at least one dominant feature. The machines are configured to fit the at least one dominant feature. Each of the controllers includes control modules integrated into an open controller platform.
The RMS also typically includes a communication system for communicating with the machines, the controllers and the material handling system. The RMS further includes a quality measurement system in communication with the communication system for measuring part or product quality after a change in the structure of the RMS. The quality measurement system includes a plurality of sensor modules. Each of the sensor modules is designed and located to provide corresponding sensor information to identify errors or faults.
The work stations may be configured in parallel, in series, or various serial-parallel configurations.
At least one of the machines typically includes a plurality of single axis drive modules.
A controller for the at least one machine is typically a distributed controller having high bandwidth communication.
The RMS typically further includes a reconfigurable system diagnostics network coupled to the controllers and the material handling system to diagnose errors or faults in the RMS.
Further in carrying out the above objects and other objects of the present invention, a computer-implemented method for designing the RMS of claim 1 to have the first desired production capacity is provided. The method includes the step of storing a life cycle economic analysis program in a computer to obtain a programmed computer. The method also includes the step of utilizing the programmed computer to determine whether an RMS is needed based on product information and market forecasts. The method further includes the steps of performing a computer level design for the RMS if the RMS is needed to obtain requirements and performing a machine level design for the RMS based on the requirements to obtain a final design for the RMS.
Preferably, the step of performing the system level design includes the step of designing the RMS to include subsystems that can be readily re-integrated into different RMS configurations.
Also, preferably, the step of performing the machine level design includes the step of designing each subsystem to be modular, integratable, customized, convertable, and diagnosable (see FIGS. 4 and 5).
Still further in carrying out the above objects and other objects of the present invention, a computer-implemented method for changing the production capacity of the RMS of claim 1 is provided. The method includes the steps of monitoring market conditions for the family of products to obtain market information and determining if it is desirable to reconfigure the RMS. If it is desirable to reconfigure the RMS, the method further includes the steps of reconfiguring the RMS at system and machine levels and ramping up the reconfigured RMS to obtain the second desired production capacity.
Preferably, the step of ramping up includes the steps of measuring the reconfigured RMS at the machine level to obtain at least one machine measurement signal, processing the at least one machine measurement signal to obtain a diagnostic signal, and modifying the reconfigured RMS based on the diagnostic signal.
Still preferably, the step of ramping up the reconfigured RMS also includes the steps of operating the reconfigured RMS to obtain a product, measuring the product to obtain a product measurement signal, processing the at least one product measurement signal to obtain a second diagnostic signal, and modifying the reconfigured RMS based on the second diagnostic signal (see FIG. 6).
In recent years, two enabling technologies for RMS have emerged: modular, open-architecture controls that allow reconfiguration of the controller and modular machine tools that allow reconfiguration of the machine hardware. These emerging technologies show that the trend is toward the design of systems with reconfigurable hardware and reconfigurable software with modularity as a key characteristic, as illustrated in FIG. 3. The ultimate goal of RMS is to have machines and systems that are designed to be reconfigurable simultaneously in hardware and software. These reconfigurable manufacturing systems will be open-ended so that they can be improved and upgraded rather than replaced. They allow flexibility not only in producing a variety of products, but also in changing the system itself.
As shown in FIG. 13 and discussed in the example in a following section, traditional dedicated manufacturing lines have high capacity but limited functionality. They are cost effective as long as the market demands production of large quantities of the same product. But with saturated markets and increasing pressure from global competition, there might be situations where dedicated lines do not operate at full capacity.
Flexible systems, on the other hand, are built with all the flexibility and functionality available, in most cases even with those that are not needed at installation time. The logic behind this is xe2x80x9cto buy it, just in case it may one day be neededxe2x80x9d. However, in these cases, capital lies idle on the shop floor and a major portion of the capital investment is wasted. These two types of waste are dramatically reduced with RMS technology. In the first case, the RMS allows one to add the extra capacity exactly when required, and in the second case to add the additional functionality exactly when needed. Further, when product demand is decreased, the RMS capacity can be reduced and the extra modular components may be reused to augment other lines that have increased product demand.
To allow rapid reconfiguration of lines and machines, reconfigurable manufacturing systems are designed at the outset to be reconfigurable. Otherwise, the reconfiguration process will be lengthy and impractical. Achieving this goal requires that an RMS possesses several key characteristics (as illustrated in FIG. 4). These characteristics are common to many production domains (machining, assembly, semiconductor fabrication, and production of consumer products). These characteristics determine the ease of reconfigurability of manufacturing systems. A system that possesses these key characteristics has a high level of reconfigurability. A system that lacks these key characteristics cannot be cost-effectively reconfigured.
Agility has been defined as xe2x80x9ca comprehensive response to the business challenges of profiting from the rapidly changing, continually fragmenting, global markets for high-quality, high-performance, customer-configured goods and servicesxe2x80x9d (Goldman et al. 1995). Agility is, therefore, more of a business philosophy that teaches an organization how to respond to the challenges posed by a business environment dominated by change and uncertainty.
By contrast, reconfigurability is an attribute designed, at the outset, into manufacturing processes and systems to enable them to be agile. Reconfiguration has been discussed in the context of computing systems (Villasenor and Mangione-Smith, 1997; U.S. Pat. Nos. 4,783,782 and 5,691,945) and products. However, reconfigurability is entirely new in the field of manufacturing systems, except for some very specialized applications like glass panel manufacture, as illustrated in U.S. Pat. No. 5,570,292, and laminated plastic tooling manufacture, as shown in U.S. Pat. No. 5,247,861. Reconfigurability in manufacturing encompasses a set of methodologies and techniques that aid in design, diagnostics, and ramp-up of reconfigurable manufacturing systems and machines that give corporations the engineering tools so that they can be agile and respond quickly to market opportunities and changes.
The above objects and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.